Vapor lock preventing device



Dec. 15', 1959 E, M, BROHL 2,917,110

VAPOR LOCK PREVENTING DEVICE Filed Oct. 11, 1956 7,7 l M 1 1/ '73 FUEL0125085705 7 l /fl\ easzem/e IN V EN TOR.

United States P t VAPOR LOCK PREVENTING .nnvrcn Earl M. Brohl, Flint,Mich., assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Application October 11, 1956, SerialNn...615,272 5 Claims. Cl. 158-36) The present device relates 'toan'irnproved vapor lock preventing device particularly adapted for usewith internal combustion. engines which are subjected to high ambienttemperatures.

Vapor locks have long been a source of trouble in the operation ofinternal combustion engines, particularly during .hot weather. 'Thevapor lock may .occur when a sufficiently large accumulation of fuelvapors collects within some portion of the fuel system and blocks theflow of fuel 'therethroug'h. Fuel systems are particularly susceptibleto vapor locks during hot weatherwhen the 'fuel system must operate inrelatively high ambient temperatures under which condition there is atendency "towards excessive fuel vaporization. As noted, fuel vapors maycollect in quantities su'flicient to cut on fuel flow until the ambienttemperatures are suitably reduced or the system is otherwise bled of thetroublesome vapors. This vapor'lockpropensity maybe aggravated when thevehicle is operated "in a relatively rarefied atmosphere, as when in amountainous area, causing a relative increase in fuel vapor pressure.thereby increasing the 'rate of vaporization.

Numerous devices have been developed for eliminating theproblem ofvapor'lock. Most of these devices, however, have beenunsatisfactoryeither because of their failure to operate properly, e.g,,failure 'to adequately vent the system or in'also permitting-the escapeof liquid fuel; or because the devices were too expensive .tocommercially incorporate into fuel systems.

It is therefore the purpose of the present invention to provide a fuelvapor venting device which is economical to manufacture and which may bereadily incorporated into .fuelsystern components .as ztheynow existjMore specifically, tthe present .device provides a mechanism .whereby:the liquid .and. vapor :fuels (are effectively .mechanically separated.in such .a way 'as to cause :no .loss or unnecessary handling of fuel.

The present vapor venting device may be incorporated in various parts ofthe fuel system, however, it has been found particularly satisfactory toincorporate such device in the fuel filtering bowl.

A further refinement of the present device is the in corporation thereinof a thermostatically controlled valve which renders the ventingmechanism inoperative under conditions where the ambient temperaturesare such as to preclude any problem arising from a vapor lockup. In thisway liquid fuel is denied egress through the venting system under alloperating conditions.

The subject vapor venting mechanism will hereinafter be described indetail.

In the drawing:

Figure 1 is a diagrammatic representation of a fuel system incorporatingthe subject invention; and

Figure 2 is a detail of the vent tube and thermostatic valveconstruction.

Referring to the drawing, a fuel system has been shown in order to placethe subject venting mechanism in an illustrative environment andincludes a fuel reservoir .10, a carburetor 12, a fuel filtering device14, a first conduit 16 connecting said reservoir and said filteringdevice and a second conduit 18 leading from the filter- :ing device 14to the carburetor 12. A third conduit 20 communicates the filtering bowlwith the reservoir 10. It is to be understood that the fuel system shownis in no way a limitation on the vapor venting device, per se, inasmuchas it is equally adaptable to various other types of fuel systems inwhich the problem of vapor lock might be present. 7

The fuel filtering device i4 is an essentiaily closed receptaclecomprising a U-shaped glass bowl 22 and a cover member 24 adapted tocoact therewith. The cover 24 has a plurality of passages formed thereinincluding an inlet passage 26 which opens upwardly into communicationwith the glass bowl to permit fuel to flow .therewithin, an outletconduit 28 communicates with bowl.22 through a centrally disposedvertical passage 30.

V The passages 26 and 28 respectively communicate with conduits 16 and18 and thereby permitting liquid fuel to flow from the reservoir throughthe receptacle to the carburetor.

fuel system.

Cover 24 includes the centrally disposed upstanding boss 34 which has ashoulder 36 formed thereon. A perforate plate 33 is centrally supportedon shoulder 36 and peripherally locked between bowl 22 and cover 24,through a suitable gasket 40.

Plate 38 is centrally vertically spaced from cover 24 to definetherewith an annular chamber 42 which communicates with the upwardlyopening end 44 of inlet passage 26.

Filter 32 comprises an inverted U-shaped element, the open end of whichis supported on plate 38 to overlay the perforations in the plate. Thusfuel flows from end 44 of passage 26 to annular chamber '42, through theperforated plate 38 into filter 32 passing therethrough into bowl 22,leaving through passages 31'? and 28.

In order that any fuel vapors which tend to accumulate in .filter bowl22 can be mechanically separated from the liquid fuel, a tube issupported on the cover 24 and projects through the boss 34. The upperend 52 of tube 50 terminates adjacent the upper portion of the 'upperportion of bowl 22 into which end 52 of tube 56? projects.

While the device as thus far described is adequate to prevent theexcessive build-up of fuel vapors within the fuel system, it has beenfound to be advantageous to provide means whereby the fuel ventingsystem is rendered inoperative during conditions when ambient temperatures are sufficiently low to preclude the possibility of vaporlock. In this way the useless bypassing of liquid fuel through theventing system is prevented The bypassing of liquid fuel may otherwiseoccur in the absence of vapor in the bowl 22.

To this end, a thermostatically controlled valve 60 is provided at theupper or open end 52 of the vent Thus any fuel vapors collecting in the3 tube 50. The valve consists of 61 fixed at one end 62 to the tube 50and reversely bent in such a way that the other end 64 sits freelyacross the open end of tube 50. The bimetallic spring is provided with aconvoluted portion 66 intermediate its ends to suitably position thefree end of the strip with respect to the open end of the tube as wellas to fix the spring rate and thereby determine the temperatures atwhich the valve end 64 will open and close. It will be seen in Figure 2that end 62 of the bimetallic spring is of arcuate form so as to conformto the shape of the tube whereas the free or valve end 64 is fiat so asto correspond to the inclined flattened open end 52 of the tube. End 62of the spring may be secured in any convenient way to tube 50 such as byspot welding.

Valve 6% is shown in the drawing in the closed position indicating anambient temperature such as to preclude excessive formation of fuelvapors. To illustrate, it has been found satisfactory to construct thespring valve 60 in a way to permit its closing at 120 F. and its openingat 125 F. These figures are, of course, illustrative and could be variedto the individual operating characteristics of the fuel system in whichthe subject device was to be incorporated.

The form of thermostatic spring valve 60 is preferred because of itssimplicity which results in reliable operation as well as economy ofmanufacture.

With the vent tube arrangement as shown, during conditions conducive toexcessive vapor formation, the vapors in the upper portion of thefiltering bowl 22 will be conducted therefrom, supra, permitting theliquid fuel only to pass on through the system. When ambienttemperatures are below a value likely to cause excessive vapor formationthe thermostatic valve 66 closes the vent tube 50 blocking the otherwiselikely flow of liquid fuel through the vent system. In this way anadequate supply of liquid fuel free of vapor-lock-forming quantities offuel vapor is always available.

I claim:

1. A vapor venting device for a fuel system comprising a closedreceptacle, a first conduit formed in said receptacle for supplyingliquid fuel thereto, a second conduit disposed in the lower portion ofthe receptacle and adapted to deliver liquid fuel therefrom, a tubedisposed in said receptacle and terminating at one end near the upperend of said receptacle, a thermostatically controlled valve cooperatingwith said one end of said tube, and a third conduit communicating withthe other end of said tube whereby fuel vapors formed in said receptaclemay be separated from the liquid fuel and vented through said tube andthird conduit when the ambient temperature is sufficiently high to opensaid valve.

2. A vapor venting device as defined in claim 1 in a bimetallic metalspring which said valve includes a bimetallic metal spring fixed at oneend to said tube and terminating at the other end in a portion adaptedto close the said one end of said tube.

3. A fuel system comprising a carburetor, a fuel reservoir and means forseparating fuel vapor from the liquid fuel, said meanscomprising aclosed receptacle, fuel inlet and outlet passages respectivelyconnecting said reservoir and carburetor with said means, a filteringelement intermediate said inlet and outlet passages for purifying theliquid fuel flowing from said reservoir. to said carburetor, a vent tubemounted within said receptacle and terminating at one end near the upperportion thereof, a thermostatic valve cooperating with the open end ofsaid tube to control the fiow therethrough, the other end of said tubecommunicating with a conduit connecting said receptacle to saidreservoir whereby fuel vapors formed in said receptacle may be separatedfrom the liquid fuel and returned to said reservoir when the ambienttemperature is sufificient to open said valve.

4. A vapor venting device for a fuel system comprising a closedreceptacle, inlet and outlet passages formed in said receptacle forsupplying and discharging liquid fuel, a tube defining a vent passageand having one end terminating within theupper portion of saidreceptacle and its other end adapted to be connected to a source of saidliquid fuel, and a thermostatic valve in said upper portion controllingthe said vent passage whereby fuel vapors formed in said receptacle mayeffect opening of said valve and consequent venting of said receptaclethrough said other end of said vent passage.

5. A fuel system comprising a carburetor, a fuel reservoir and a devicefor separating fuel vapor from liquid fuel, said device comprising aclosed receptacle, fuel outlet and inlet conduits connecting saidreceptacle with said carburetor and reservoir respectively, a vent tubedefining a flow passage terminating at one end in an upper zone of saidreceptacle, said vent tube communicating with said reservoir, athermostatically operated valve associated with. said tube within saidupper zone of said receptacle to control said flow passage, and thearrangement being such that the temperature of fuel vapor in saidreceptacle may effect operation of said valve thereby opposing vaporlock tendencies in the system by venting said vapor through said flowpassage to said reservoir.

References Cited in the file of this patent UNITED STATES PATENTS1,849,590 Phillips Mar. 15, 1932 1,941,390 De Lancey Dec. 26, 19332,323,525 Ebel et a1. July 6, 1943 2,545,856 Orr Mar. 20, 1951

